> The best resolution may be through Ads billing, by trying to post an ad and reporting a problem displaying an ad
Something kind of like that worked at the job I a few years ago.
A large provider of free email that also runs an ad network (not Google or Microsoft) once kept flagging my employer's emails as spam. The only emails we sent were receipts to people who had purchased stuff from us, an email with installation and activation instructions to new purchasers, and replies to support tickets.
We'd go through their procedure to report false positives, and anywhere from a few days to a week later our mails would start going through...and then a few weeks later they'd start getting blocked again.
This finally ended permanently when our guy who managed ad spending called up our rep at the email provider, and asked something along the lines of "Could you explain to me why the fuck I'm spending $X thousands dollars a week on ads there to acquire new customers, and then you block us from sending those customers receipt and instructions!?".
The ad rep put him hold for a moment, and then returned with their head of IT conferenced in. The ad rep explained the problem to the IT head. The IT head then conferenced in the leader of the anti-spam team and told him to add our domain to an exception list so that nothing we sent could ever be classified as spam. The anti-spam team guy said it would be done in 10 minutes.
We never had a problem after that.